A passive formaldehyde monitoring device capable of emitting an audible warning signal is described. Monitoring exposure to formaldehyde is mandated by OSHA for certain industries. Currently, passive collection devices typically contain absorbent material that physically entraps formaldehyde from the air; laboratory analysis of the formaldehyde in these devices can take extensive time periods. The monitoring device proposed herein is a biosensor capable of detecting low ppm levels of formaldehyde from the atmosphere. Formaldehyde triggers a series of electrochemical reactions that power an audible signal device contained within the monitor. The amounts and ratios of biosensor materials may be adjusted to trigger the alarm at desired, predetermined concentrations of formaldehyde. This obviates the need for laboratory analysis, enables immediate determination that exposure limits have been exceeded, and permits rapid steps to be taken to ameliorate a toxic exposure episode. PROPOSED COMMERCIAL APPLICATION: The commercial potential of Audible Formaldehyde Monitoring Device can be expected to be very wide, as this product can be used in industries, such as formaldehyde manufacturers and other chemical manufacturers that use or generate formaldehyde in their processing techniques.